I like how people went ahead and said the exact things that we try to avoid in discussion threads :/
Don't just say "they power hungry jerks, they need restrictions hurr durr" Back it up. Proof. Logical reasoning. One event should not be the basis for mass judgement.
That being said, the justice system isn't all that "just" to begin with. People who are rich or famous, along with those who are a part of law enforcement, receive significantly reduced punishment compared to those who are normal citizens. The rules are tipped to their favor and, as a bureaucratic office, it would take a while to implement change. It's a large system and, in theory, by implementing such a change, they would be required to have a retrial for every case that might have been influenced by the change. Which is expensive. It's rare for such a measure to get passed, but it's possible if somebody persists hard at it.
Also, a part of this incident is due to very vague guidelines concerning tasers. They're still a relatively new implement in a police officers arsenal, designed to be a less lethal alternative to their pistol. However, the guidelines for usage are vague, so a police officer has to use judgement on the fly to decide if it's necessary. Often, the police officer doesn't want to risk his life and limb any more than he has to, so defensive measures like pepper spray and tasers get used very quickly because the cop doesn't want to risk the possibility of it spiraling out of control, where either he, or the suspect, could get seriously injured or killed.
And specifically, THESE police officers abused their power. They should be suspended without pay until an official investigation determines the exact details, then deal judgement upon the findings. Considering the situation, that judgement should probably be loss of job and time in jail.